1. Field of the Invention
This invention relates to an air bag inflation gas generator used to inflate air bags such as air bags for impact safety devices, life jackets, rafts, and escape chutes, and particularly to a gas generating agent disposed within the device to generate a combustion gas.
2. Description of the Known Art
A known shock absorber to protect a passenger car driver from shocks at a collision accident comprises an air bag having a capacity of, for example, 60 liters and a gas generator to inflate the air bag with gas. At a collision accident of a passenger car, explosives or other gas generating agents having a similar composition thereto, which are charged in the gas generator, are ignited and burnt to produce gas. The air bag is instantaneously inflated by the resultant gas to protect the driver against any collision shocks, thereby avoiding possible serious injury of the driver.
FIG. 7 shows a known air bag inflation gas generator disclosed in Japanese Patent Application Laid-open Print No. 155857/1990. In the drawing, the reference numeral 11 shows a combustion chamber containing a plurality of gas generating agents 13 in the stacked state.
The gas generating agents 13 are a circular plate having a through hole 15 at the center, and the through hole 15 accommodates an ignition agent 17.
These gas generating agents 13 are accommodated in a concealed container 19. At the center of this concealed container 19, a concave part 21 is formed to be depressed toward the through hole 15 of the gas generating agents 13.
In the concave part 21 is provided an igniter 23 to burn the gas generating agents 13.
The combustion chamber 11 has a combustion chamber filter 25 disposed along its inner wall. And, a plenum chamber 27 annularly surrounds the combustion chamber 11 and receives gas flow through an orifice 26 from the combustion chamber filter 25.
The plenum chamber 27 contains a plenum chamber filter consisting of an upper filter 29 and a gas filter 31.
And, the plenum chamber 27 contains a gas outlet 33 to supply the gas flow from the gas filter 31 to an air bag.
In this type of air bag inflation gas generator, the powder in the igniter 23 burns the ignition agent 17 when the igniter is energized. The ignition agent 17 in turn causes the gas generating agents 13 to burn. Gas from the gas generating agents 13 flows into the plenum chamber 27 through the combustion chamber filter 25 disposed along the inner wall of the combustion chamber 11. The gas is then purified by the upper filter 29 and the gas filler 31 and flows into the air bag through the gas outlet 33. The air bag can be completely inflated within a very short time, for example, approximately 0.04 second.
The known air bag inflation gas generator, however, has drawbacks that the assembling steps are increased and the production costs are increased because a separator 35 is disposed between the gas generating agents 13 to hold the gas generating agents at certain intervals and to ensure the combustion efficiency of the gas generating agents 13.
Since the gas generating agents 13 have the shape of a plate, they may be cracked or chipped when a bending stress or pressing pressure exceeding a certain level is applied during or after stacking them.
Furthermore, since the gas generating agents 13 have the shape of a plate, the separator 35 may prevent the ignition by the flame of the ignition agent 17.